Fertilizers have been used for millennia to enhance the growth of plants. Fertilizers can affect the plant's rate of growth; its hardiness in the face of high and low temperatures, insects, fungus and bacteria; soil alkalinity, soil moisture, and other factors affecting growth. The components of the fertilizer and their proportions change the effectiveness of a fertilizer.
Fertilizers typically contain macronutrients nitrogen, phosphorus and potassium, and micronutrients such as minerals and metals. The source of the nutrients can be from animal matter, plant matter, or synthetic ingredients formed by chemical reactions. Both organic (carbon-containing molecules from animals or plants) and inorganic ingredients can be found in fertilizers.